The present invention relates to a method and means for filling of bulk material, especially fluidized material, into flexible containers.
The method comprises filling of bulk material into a flexible container having lifting loops which are placed on a double, load carrying hook while the container bottom is placed on a carrying plane. The bulk material is filled into the container through a filling pipe comprising means for supplying air to blow up the container. The means for carrying out the method comprises a double, load carrying hook with holding devices. It further comprises a filling pipe for the bulk material and supply pipes for air and possibly also dust removing means. This filling apparatus also comprises a carrying plane against which the container bottom rests during the filling operation.
Filling of bulk material into flexible containers and making them ready for further transport can be carried out in different ways and applying different types of equipment adjusted to the actual purpose. Application of flexible containers for one special type of bulk material, i.e. fluidized material, has been highly desired. In this field there is an increasing demand for efficient solutions which make it possible to use flexible containers. During filling of fluidized material such as cement, special problems occur because the container just after having been filled is not stable. Such material gives special problems during the filling operation, but even more so during further transport and storage right after the filling operation. It has been found that it is very difficult to rapidly remove air, which gets into the container during the filling operation of the bulk material, from the container.
This implies that immediately after the filling operation, the container filled with fluidized material, behaves as if it were filled with a liquid. Therefore, the container cannot simply be disconnected from the filling apparatus and transported directly on a conveyer belt or left standing on a pallet, because it quite easily will tilt or sink to the ground.
Several methods have been attempted to solve these problems in order to arrive at efficient applications of flexible containers for fluidized material. One method used comprises filling the container while it is hanging on the forks of a truck and thereupon transport the container to storage immediately after the filling operation is completed.
Further there are known filling apparatuses for filling the container while it is hanging from its lifting loops (described in British patent application No. 2.022.545). This apparatus comprises a filling pipe which can be raised or lowered and which is arranged in a stationary or movable supporting frame. Hanging the container, including its inner bag, connecting and disconnecting this bag from the filling pipe, is however very complicated. Further it is quite labour consuming to release the lifting loops from the holding device and put them on to a hook or fork for transport of the container away from the filling apparatus. This apparatus is best suited for use in connection with a conveyer belt for further transport of the container. Accordingly it will be complicated to adjust this apparatus for economic filling of fluidized material.
Another filling apparatus is described in Norwegian Pat. No. 147,142, belonging to the applicant and having. According to this arrangement the bulk material is filled through a filling pipe which can be moved somewhat horizontally while the container is hanging by its lifting loops on a wide hook which can be moved both horizontally and vertically. The container bottom rests against a conveyer belt or a plate, and when the lifting loops are disconnected from the hook the container is standing without support on the conveyer belt by its whole weight. If this apparatus should be applied for filling fluidized material, there would be a great risk that the filled container would tilt as soon as it was disconnected from the hook. The lifting loops can not be released from the hook without lowering it and releasing the hook from its load. It has been found that this apparatus is not suited for filling of fluidized material.
Vibration of the container during or subsequent to filling in order to solve the associated with the fluidizing air was also studied by the inventors. However, this procedure did not turn out to be successful. Considering their own experience and knowledge of other people's experiences using this technique, the inventors found that the problem had to be solved in other ways.
The known technique, comprising hanging the container from the forks of a truck during filling and weighing, was further studied in order to find out more about its technical advantages. According to this method the container is transported subsequent to filling, while it is hanging from the forks of the truck, to a temporary storage site. Here the container is released from the forks, and the truck returns and a new container is put on the forks for filling. However, this operation requires at least two trucks in order to secure continuous application of the filling apparatus.
One variant of this technique comprises hanging the container during filling from a holding device which can be dismantled. The complete holding device, including the container hanging on it, is disconnected from the filling apparatus and transported by a truck to the temporary storage site, and there the holding device is manually released from the container and returned to the filling apparatus. Thus the need for several trucks is reduced, but continuous filling will then require several holding devices. The release of the container from such a device will also be labour consuming.